Throttle valve for carburetors and other conduits



Jan. 27, 1942. .E. DODSON 2,271,390

THROTTLE VALVE FOR GARBURETORS AND OTHER GONDUITS Filed May 8, 1940 2 Sheets-Sheet 1 A M I W I91.

/ I. II

Jan.27, 1942. E. DODSON 2,271,390

THROTTLE VALVE FOR CARBURETORS AND OTHER CONDljITS- Fiied May a, 1940 2 sheets -sheet 2 v /IIIIIIIIIIIIIA Patented Jan. 27, 1942 THROTTLE vALvE FOR- CAR BURETO ItS OTHER. CONDUITS I Edward Dodson, Putn ey iieath, London, England Application May 8, 1940, Serial No. 334,077

, InGreatBritain ay 19,1939" 1 t 12 Claims. gcl. 251-11) This invention relates to throttle valves'for carburetors but it may also be applied to such valves used in other conduits for controlling the flow of air or other fluid therethrough.

The usual butterfly throttlevalve for aero en gine carburetors consists of a plate or disc'of approximately elliptical cross section arrangedto extend obliquely across the induction pipe 'or other conduit to close it, said disc being turned in opening aboutan axis extending diametrically through said conduit. The face'of the disc against which the stream impinges will be hereina'fter referred to-as the upstream face, and the other face of the disc will be hereinafter referredQ v 153 ,IlFigures 11 to '4respectively are. side elevations to as the downstream face. Moreover, o'ne'edge' of the disc will meet the stream before the other; 'the first edge being hereinafter referred to as the leading edge and the second edge as the trailing edge. Such discs have hitherto been made to I v Figure 5 'is a vertical section through the throt-' balance geometrically and therefore become unbalanced dynamically when the stream is flowing. Loads of the order of 48 inch pounds are experienced, in the case of aero engine Icarburetors, tending to keep such throttle valves closed and further the load in large aero engine carburetors is irregular and tends to attain maximum values in the neighborhood of twenty jdegrees of throttle opening. v 3

Owing to this irregularity difliculty is experienced in accurately controlling the power of the engine through the necessarily light control mechanism extending between the pilot's lever" and the throttle valve.

One of theobjects of this invention is to shape 1 the throttle valve so as to relieve the aerodynamic loading. Another object is to reducethe power increment per degree of openingof the throttle valve in the early stages of its movement from the closed position and therebyprovide greater delicacy of control which is particularly'desired in aircraft when taxi-ing or making an approach to a landing.

The throttle valve according to this invention i is constituted by a disc shaped toreduce the aerodynamic loading on the valve by the provision of a bulge at the leading edge on the down;

stream side of the disc, or' by the provision on the upstream side of the disc adjacent to its 'tr ailing edge of a concave depression.- Preferably the throttle valve is formed both with the bulge adjacent to its leading edge and with the concave depresison adjacent to its trailing edge.

The effect of the bulge adjacent to the leadin edge is to fill up a space wherelasa result'of' the stream, a local reduction in pressure and eddies tend to form, While. the effect of the co n cave depression adjacent to the trailing edge is to divert the stream insuch a way that the re action caused by such diversion will tend toopen the throttle valve. Each of these alterations contributes .to the desired result and may be used separately but by using both of" them the peak load may be reduced by nearly 80%, and also occurs at a considerably greater throttle opening,

1 9 Where delicacy of control is no,v longer so important.

The invention will now be explainedin greater tle valve shown in Figure 4,

Figures 6 and 7 are elevations of two further forms of the throttle valve ,a'ccordingto. the inpn v. .7

' as, n an or; theifigures the air is assumed to new frornabove in the direction of the arrow sho wn in F g e I The known form ofjthrottle valve, on writhing valve according to the invention represents an improvement, isconstituted by a discofapproxi-,

mately' elliptical cross-section arranged to lie obliquely across the. induction pipe when .in the closed position. The load curve representing the load required to open such a throttle'fvalve in pounds plotted against throttle opening in ,de-

grees has a very markedfpeak at about twenty, degrees" throttle opening. One of the. objects of the invention is to reduce the aerodynamic load. on the throttle valvewhich tends to close it andl t nalso to render this load as uniform 'as possible throughout the range of throttle opening.

The throttleval-ve' l5 shown in'Figure l differs from the, known form by the'pr'ovision of a bulge H at the leading'edge on the downstream side.

5 11115 bulge fills up thel space in which ,e'ddiesf form in .thecase of the known throttle valvel' Although the loadi'curve of thevalveshown' in Fig. 1 un exhibits a marked peak at "about 70 twenty ,degrees throttle opening, the load ithroughout the early stages of opening is very' materially reduced as compared with the known throttle valve. It will be observed that, viewing the bulge in sectionandinthe closed position. 755 of the valve as shown in l igure l, the edge-of the valveextends downstream from the point at throttle valve shown in Figure 1 and which doesnot completely fill the eddy area, the straight portion of the edge of the bulge terminatingsomewhat on the upstream side of the pivotal axis of the disc. In addition to: being provided with the bulge ll, the throttle. valve in Figure 2..

has a concave depression l8 at its trailing edge.

on the upstream side. The efiect of this is to divert the airflow and produce a reaction on the throttle valve tending to move it towards the open position. The load curve for this throttle valve is of similar form" to that for the throttle valve according to Fig. 1 and shows a'considerable improvement over'the load curve for the known throttle valve;

In the case of the throttle valve shown in Figure 3 the bulge I! is larger than that shown in Figure 2 and of about the same size as that shown in Figure 1, the straight portion of the edge of the bulge again terminating at a point level with the pivotal axis of the disc. The bulge consequently fills up the whole of the eddy" space. In addition the extreme trailing edge of the disc on the upstream side, which constitutes the outer' portion of the concave depression" I8; is swept up as shown at l9 away from the central plane" of the throttle and towards the stream. This represents a very considerable improvement from the point of view of reduction in aerodynamic loading over the throttle valves shown in Figures 1 and 2-.

Itwill be observed'that in the case of the'valve shown in Figure 3" there is a concave depression at the trailing edge on the downstream' side.

In the case of the valve shown in Figure 4' this.

depression is removed. The load curve for the throttle valve illustrated in Figure 4 is generally similar to that shown in Figure 3' but has improved-characteristics at low throttle, openings. A comparison of these two load curves indicates that the provision of a depression 20' on the downstream side of the trailingedge is without material effect;

The throttle valve shown in Figure 6' differs from that in Figure 4 in that the portion 2| at the trailing edge on the downstream side is curved to lie approximately parallel to the swept up portion IQ of the trailing edge on the upstream side. This gives a further improvement in the load curve. 7

The throttle valve shown inFigure 7"is similar to that shown in Figure 6 except that the leading edge is roundedoff at 22 on the upstream side and this form of throttle valve proves to give the best results of all.

In addition to effecting a, reduction in aerodynamic loading on the valve, the invention gives a further important advantage, namely, less rapid development of power per degree of throttle opening consequent upon the, slower opening of the valve.

The effect of the changesof shape at the leading and trailing edges of the disc in the valve according to Fig. 4 as compared with the known valve is to produce a very much slower unmasking of the induction pipe as the valve is opened. This is due to the fact, firstly, that the straight portion of the edge of the bulge terminates at a point level with the pivotal axis of the disc, the nose portion of the bulge ll being curvedtoasmall radius 23 and, secondly, to the fact that the end 24 of the upswept trailing edge IS- lies considerably above the point- 25 at which the central plane of the disc meets the wall of the induction P 19 Although in the case of the valve shown in Figure 4 the areas of the induction pipe unmasked at the leading and trailing edges respectively of the valve. are considerably smaller than the. corresponding areas in the case of the known throttle-valve, the area unmasked at the trailing edge is greater than that at the leading edge. This i'san important advantage because it facilitates the transfer of fuel from the slow running jet l6 throughthe transverse passage- 28 which is shown inF-igure- 5.

When the-engineisidling substantially no fuel is picked up from' the-main-jet, which is not shown but is to be understood as located above the throttle valve in each of the figures, owing to' the small quantity of air which is-being drawnthrough the induction pipe. Under these condi tions the whole of the fuel supply is' drawn'fromthe slow running jet l6; This jet is providedwith two fuel passages 29, 30- and inthe earlystages of throttle opening the fuel supply through the lower passage'S-U' is diluted with air drawn throughthe upper passage 29. case of the valve shown in- Figures 4 and 5 a groove 31* is provided at the leading edge ofthedisc to give access for'the'passageot air-throughthe fuel passage 2'9.

As however the valveg-radua-l-lyopens; it be--' gins to choke'thesupply of air through the pas-- sage 29; as will be understood from a consideration of the position ofthe' valveat ten degrees opening, as shown chain-dotted lines in Fig-- ure 4: Under these conditions both passages 29',

3 0Tdeliver'fuel from the slow running jet I6, this compensating forthedecreased suction at the fiat spot which occurs just before the main fuel supply comes into operation.

Owing to the increased-area of unmasking at thetrailingedgeof the valve 3. grea-ter-quantity of fuel will be drawn through thetrans-verse passage 28* and, as will be seenfrom the chaina dotted position of the valve in Figure 4, a Venturi' shaped aperture 32 isopened at thetrailingedge of the valve which produces a dynamic suction on the transverse passage and consequently facilitates the: transfer of f-ueltherethrough;

Slow running'jets are also providedin the-case of the valves shown in the remaining figures,

ing. with the result that greater delicacy of con-f trolls obtained.

As will be. observed from Figures 4 and 5, it

is convenient inthe caseof the valveaccording to the invention to build up the disc of separate upper and lower portions 33, 34 which are separately. keyed to thevalve spindle 35 and are In the to form a bulge, the edge of which, viewed in secunited by screws, (not shown). Figure 5-,shows ,tion in the closed position of the valve, extends how the transverse passage "isicurved upwardly at 38 to pass over the spindle,.3,5.: It also illustrates the formation of registering,cavitiesx39,

40 in ,the two portionsoftheldisc for.thepurpose of reducing its weight; i c I Although the invention hasbeen described primarily with reference toits application to. throttle valves for aero engine carburetors, it will be .un-

derstood that it is in nowise limited to this par- .ticular application but may be applied .to butterfly throttle valves generally and'consequently has -many applications.

What I claim as my; invention and desire to secure by Letters Patent is: f- ,1 h

1.A butterfly throttle valve, whichis constitical section of the disc being thickened on that side which is to face downstream-in service to form a bulge, the edge of which, viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge 3 of the central plane of the disc meets the wall of the conduit in a direction substantiallyparallel to the direction of flow and then turns inward to merge with the downstream faceof the disc, the change of direction occurring at a point somewhat on the upstream side of the pivotal axis of the disc.

2. A butterfly throttle valve, which is constituted by a disc of approximately elliptical cross section arranged to pivot about a central axis at right angles to the elliptical section and to extend obliquely across a conduit to close it, the elliptical section of the disc being thickened on that side which is to face downstream in service to form a bulge, the edge of which, viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turns inward to merge with the downstream face of the disc, the change of direction occurring at a point in the plane through the pivotal axis of the disc at right angles to the axis of the conduit.

3. A butterfly throttle valve, which is constituted by a disc of approximately elliptical cross section arranged to pivot about a central axis at right angles to the elliptical section and to extend obliquely across a conduit to close it, the elliptical section of the disc being thickened on that side which is to face downstream in service to form a bulge, the edge of which, viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turns inward to merge with the downstream face of the disc, the change of direction occurring at apoint somewhat on the upstream side of the pivotal axis of the disc, and the'disc being formed with a concave depression near its trailing edge on the upstream side.

downstream from the point at which the leading Jedge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turnsinward to merge with the downstream'face of-the disc, the change of directionoccurring at a point in the plane through the pivotal axis of the disc at right angles to the conduit, wall, and the disc being formed with a concave depression near its trailing edgeonthe upstream side.

.5. A butterfly throttle valve, which is constituted by a disc of approximately elliptical cross section arranged to pivot about a central axis at right angles to the elliptical section and to exedge'of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turns inward to merge with the downstream face of the disc, the change of direction occurring at a point in the plane through the pivotal axis of the disc perpendicular to the conduit wall, the disc being formed with a concave depression near its trailing. edge on the upstream side, and the extreme trailing edge of the disc, on the upstream side,

which constitutes the outer portion of said concave depression, being swept away from the central plane of the disc.

6. A butterfly throttle valve as claimed in claim 5, in which the portion of the trailing edge of the disc on the downstream side thereof is curved to extend approximately parallel with the upstream side of said trailing edge.

7. A butterfly throttle valve as claimed in claim 4, in which the leading edge of the disc is rounded off on the upstream side.

8. A butterfly throttle valve, which is constituted by a disc of approximately elliptical cross section arranged to pivot about a central axis at, right angles to the elliptical section and to extend obliquely across a conduit to close it, the elliptical section of the disc being thickened on that side which is to face downstream in service to form a bulge, the edge of which, viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantial.- ly parallel to the direction of flow and then turns inward to merge with the downstream face of the disc, the change of direction occurring at a point somewhat on the upstream side of the pivotal axis of the disc, the disc having a transverse passage for a supplementary supply of fuel for slow running, and the trailing edge of the disc being arranged to expose a larger area of the conduit than the leading edge as the valve is opened.

9. A butterfly throttle valve, which is constituted by a disc of approximately elliptical cross section arranged to pivot about a central axis at right angles to the elliptical section and to extend obliquely across a conduit to close it, the elliptical section of the disc being thickened on that side which is to face downstream in service to form a bulge, the edge of which, viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the directionof flow and then turns inward to merge with the downstream face of the disc, the change of direction occurring at a point in the plane through the pivotal axis of the disc perpendicular to the conduit wall, the disc having a transverse passage for a supplementary supply of fuel for slow running, and the trailing edge of the disc being arranged to expose 'a larger area of the conduit than the leading edge as'the valve is opened.

7 10. A butterfiy'th'rottle valve, which is constituted bya disc of approximately elliptical cross section arranged to pivot about a central axis at right angles to the elliptical section andto extend obliquely across a conduit to close it, the elliptical section of the disc being thickened on that side which is to face downstream in service toform a bulge, the edge of which,v viewed in section in the closed position of the valve, extends downstream from the point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turns inward to merge with thedownstream .liptical section of the disc being thickened on that side which is to face downstream in service to form a bulge, the edge of which, viewed in section inthe closed position of the valve, extends downstream fromtthe point at which the leading edge of the central plane of the disc meets the wall of the conduit in a direction substantially parallel to the direction of flow and then turns inwardtomerge with the downstream face of the disc, the change of direction occurring at a point within the range defined as including the plane through the pivotal axis of the disc perpendicular to the conduit wall and other points on the upstream side only of said axis.

12. A butterfly throttle valve which comprises a conduit and a disc arranged to pivot about a central axis and to extend obliquely across the conduit to close it, said disc formed with a bulge on its downstream side at and forming it leading edge, the said leading edge shaped in part to conform with the wall of the conduit when the valve is closed andbeing curved on the downstream side toward the pivot axis to merge with the downstream face of the disc, that portion of the leading edge of the bulge which conforms with the conduit wall in the closed position of the valve being "entirely on the upstream side of the plane passing through the axis of the disc perpendicular to the conduit wall.

EDWARD DODSON. 

